General digital video disks (DVDs) are storage media which can store a variety of digital information such as video information and audio information. In particular, DVD movies have the convenience and various functions that cannot be found in existing storage media. Among captions used in DVDs, captions that are used for people who have difficulty in hearing or for the purpose of learning can be produced in a maximum of 32 different languages and inserted, so that a user can easily select and watch a desired language in a movie.
FIG. 1 illustrates the entire process for producing a DVD film. Referring to FIG. 1, in the first stage, there is a film selection step 1 in which a film to be produced as a DVD title is selected among released films or to-be-released films. The second stage includes a video data encoding step 2, an acoustic data encoding step 3 and a sub-picture producing step 4. In the video data encoding step 2, the master of the selected film is encoded in an MPEG-2 file format suitable for a DVD manufacturing through a telecine operation. In the acoustic data encoding step 3, the format of a multi-channel sound in the selected film is converted into a format suitable for a DVD acoustic format, for example, AC-3. Multilingual audio support which covers a maximum of 8 languages is carried out in the step 3. The sub-picture producing step 4 is for performing a menu function and processing a caption on a DVD. Moving pictures and still pictures can be used on a menu, and multilingual captioning can cover a maximum of 32 languages. The third stage includes a DVD authoring step 5 in which a picture, a sound, a menu and a caption are united and an area code, a copying prevention code and the like are added to the united result to thereby form a stream. The fourth stage includes a step 6 in which the thus-formed stream is stored in a large-capacity storage medium such as a digital layer tape (DLT) or a DVD-ROM.
FIG. 2 is a flowchart for illustrating a conventional DVD caption producing process. Referring to FIG. 2, a time code is extracted from a moving picture 11 to be produced for DVDs, using a text file 10 of a primitive multilingual caption, in step 12. A caption corresponding to each language is inserted according to an extracted time code, in step 13, while the caption is produced in the format of a graphic file BMP or a text file, so that the graphic file BMP or the text file is adjusted corresponding to the time code. Then, the caption corresponding to each language undergoes a timing inspection for determining whether a caption generation point and a caption concluding point are proper and undergoes correction, in step 14. A primitive file into which a time code has been completely inserted is converted into a script dedicated file, in step 15. Thereafter, the script file is finally input to a DVD authoring program 16.
In a conventional DVD caption producing process as described with reference to FIG. 2, a caption for DVD films is produced and inserted in the format of a graphic file or test file in an authoring process. Also, generation of a time code for designating a caption generation point and a caption ending point is complicated and time-consuming in the case of moving pictures which require a two-hour running time on the average and no less than 1500 times of captions for movie speech. Therefore, in case that a caption is inserted in a plurality of languages, a caption corresponding to each of the languages must be inserted, so that additional working time and costs depending on the number of languages added are required.